[time-nuts] Fun with the Z3815

Morris Odell vilgotch at bigpond.net.au
Sat Aug 11 07:27:19 EDT 2012


HI all,

I posted a question recently here for a friend re a Z3815 not receiving,
having formerly been perfect.  Here's what he says now:

" I've done more testing with my HP3815A. Firstly I rewired the coax cable
between the external antenna connector and the PCB - there was some evidence
of snagging on the outside of the cable where it passes through the metal
casing. However, no improvement in performance resulted. Also the blocking
capacitor referred to turns out to be an inductor. DC is making it through
to the antenna amp, and there is continuity along the whole route from
N-connector to the Furuno GPS receiver input.

The status screen on Hyperterminal shows that something is happening,
however. The SYNCHRONIZATION section on the display showed outputs invalid,
TFOM = 9 and FFOM = 3 (i.e. no sync). But the ACQUISITION section showed
that although no satellites had been tracked, several had been detected - in
fact 9 of them.  Also, the correct date and time were displayed. The LAT and
LONG data was incorrect, being the original northern hemisphere figures.
Health monitor reads OK and there are no ALARMS. So the receiver appears to
be picking up enough information to show the satellites' PRN, EL and AZ (and
furthermore they change between readings) as well as the date and time.
What's more the time displayed is local time!"

Any suggestions as to what's going on?

Morris





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